Lubricant compositions and detergent additives therefor



United States Patent ware No Drawing. Filed Apr. 11, 1966, Ser. No. 541,488

7 Claims. (Cl. 252-467) This application is a continuation-in-part of application Ser. No. 264,026, filed Mar. 11, 1963, and now abandoned.

This invention relates to lubricant compositions possessing enhanced antioxidant, anticorrodent and detergency characteristics. More specifically, it relates to compositions containing, as ashless additives, small amounts of substances which are produced by reacting phosphosulfurized polyisobutylenes with certain polyamines.

Most mineral lubricating oils when used in internal combustion engines, particularly engines such as diesel type engines which are operated under severe conditions, undergo oxidative deterioration resulting in the production of acidic and abrasive materials harmful to metal surfaces. These and other oxidation products deposit upon the engine parts, for example, upon the valves, rings and pistons resulting in resinous or varnish-like films.

It is an important function of modern lubricants, in addition to reducing friction between moving parts of an engine thereby reducing wear, to prevent the formation and deposition of solid products upon the engine parts. These products are usually in some measure attributable to the lubricant itself and especially to certain metal-containing additives used therein.

As indicated above, a certain amount of the deposits formed on engine surfaces are decomposition products of the lubricating oils themselves. However, an additional amount of deposit is a metallic ash directly attributable to the decomposition of metal containing additives which are added to impart certain desired characteristics to the lubricant compositions. Particularly, additives which are added to increase the detergency of lubricant compositions commonly contain a metallic component. Thus, a common result is that these types of additives, specifically added to reduce deposit formation, themselves contribute deposits which are prone to deposit on the spark plugs and valves causing wear and reduced engine efliciency.

Most of the detergent additives which have been used on a commercial scale are organic, metal-containing compounds, such as calcium petroleum sulfonate, calcium cetyl phosphate, calcium octyl salicylate, calcium phenyl stearate, the barium salt of wax-substituted benzene sulfonate and the potassium and barium salts of the reaction product of phosphorus pentasulfide and polybutene.

The precursors of the compounds of the last-named type, namely, phosphosulfurized hydrocarbons, and particularly those obtained by reacting a phosphorus sulfide with an alkane or an olefin, are known in the. art as exhibiting detergent effects, i.e., reducing amount of the engine deposits. However, the unneutralized products are suflficiently acidic that their addition adversely affects the corrosive and rusting tendencies of the lubricant compositions. Neutralization of these types of compounds with metallic oxides and hydroxides as, for example, in the aforementioned barium and potassium salts, results in improving the anticorrosive and antioxidant characteristics. However, as mentioned before, it also results in ash-forming metallic constituents, Therefore, it is an object of this invention to provide a detergent type additive that is ashless and in addition possesses excellent anticorrosive, antioxidant and antiwear characteristics.

Phosphosulfurized hydrocarbons which are neutralized by nonmetallic bases are known in the prior art to have good detergent qualities. Examples of such bases that have been used are amines, ammonia and nitrogen containing ring compounds, such as pyridine, quinoline, etc. However, in most cases, a certain amount of a metallic constituent is added and in no case do the prior art, nonmetallic additives possess the excellent detergency, anticorrosion, antioxidant and antiwear characteristics displayed by those of this invention. US. Patent 3,143,506 discloses salts of amines and polyamines which are produced by reacting under reflux conditions a hydrocarbyl thiophosphonic acid with the amine for a period of 0.5 to 2 hours, followed by nitrogen blowing at a temperature of from to 220 C.

It has now been found that lubricant compositions possessing excellent detergency and anticohesive properties and surprisingly superior antiwear (extreme pressure) and antioxidant properties can be formed by combining with a mineral lubricating oil a minor amount of the material produced by reacting for a period greater than 4 hours at a temperature of from about 200 to 500 F., (A) a phosphosulfurized polybutene and (B) an amine represented by the general formula wherein at is an integer from 1 to 9.

Thus, in a preferred form, the additive of this invention is a material produced by reacting at a temperature of about 300 F. for a period of from 4 to 24 hours, (a) the reaction product of P 5 and an isobutylene having a molecular weight of about 915 and (b) triethylene tetrarnine.

While this represents the preferred product, efltective additives result when a hydrolyzed phosphosulfurizedpolyisobutylene is used. Thus one may, after obtaining the polyisobutylene-phosphorus pentasulfide product, further react this product with H O to obtain what is herein termed a hydrolyzed reaction product. These products are further reacted with the polyamines of the invention to obtain effective detergent additives.

Polyisobutylenes suitable for the reaction with phosphorus pentasulfide are those having a molecular weight between 250 and 1500, and preferably between 500 and 1000. A preferred species is a polyisobutylene having a molecular weight of about 915.

The phosphorus sulfide-polyisobutylene reaction product may be readily obtained by reacting the olefin With a phosphorus sulfide, such as P S at temperatures between about 200 and 500 F. using between about 5% to 25% by weight of the phosphorus pentasulfide. Reaction under a nonoxidizing atmosphere, such as nitrogen, is preferable. An inert diluent, such as mineral oil, may also be used to simplify handling of reactants. Use of an equimolar amount of the phosphorus pentasulfide is preferred be cause further purification of the product is then simplified. However, an excess of the phosphorous sulfide can be used and the unreacted portion removed by filtration or a combination of filtration and distillation. Conversely, a stoichiometric excess of the polyisobutylene may be used and separated from the reaction product. The reaction must be continued for a period of at least 4 hours and usually not more than 30 hours. As disclosed in US. 3,143,506, previously mentioned, a reaction time of up to about 2 hours is sufficient to produce a simple amine salt. It cannot be stated with a degree of certainty what materials are produced by the increased reaction period; however, it is obvious from IR analyses comparing materials prepared by heating over protracted periods, that fundamental changes take place indicating a difference from the simple salt structures formed upon initial heating. Though it has been widely theorized that no amidification will take place upon simply heating an amine and a thiophosphonic acid together, it is possible that this does occur in some degree. In any event, it is most significant that oil compositions containing minor amounts of these additives show greatly enhanced extreme pressure characteristics and antioxident characteristics when compared with compositions containing the simple salts.

The following examples are illustrative of the preparation of the additives of this invention and are not intended to limit the scope of the invention.

EXAMPLE I.PREPARATION OF PHOSPHORUS PENTASULFIDEPOLYISOBUTYLENE REACTION PRODUCT 2.5 kg. of polyisobutylene having a molecular weight of about 900 was placed in a reaction flask equipped with a thermometer and a stirrer, 400 g. of phosphorus pentasulfide was added, the mixture was blanketed with nitrogen and heated to 450 F. The mixture was held at that temperature with constant stirring for a period of 18 hours. The resulting product was filtered hot through diatomaceous earth in order to remove unreacted phosphorous pentasulfide. The yield was 2613 g. of a material which analyzed 3.91% phosphorous and 8.19% sulfur.

EXAMPLE II.HYDROLYSIS OF PHOSPHORUS PENTASULFIDEPOLYISOBUTYLENE REACTION PRODUCT 1350 g. of the product of Example I was dissolved in 1150 g. of 150 neutral oil and placed in a reaction flask equipped with a thermometer, stirrer and a burette. The mixture was blanketed with nitrogen and heated to 230 F. Water was added through the burette at a rate of about 0.2 ml. per minute as the temperature was raised slowly to 300 F. The water addition rate was then increased to 0.7 ml. per minute and the temperature was held at 300 F. Addition of water was continued until a constant acid number was reached. A total of 250 ml. of water was added. 2443.8 g. of hydrolyzed P S -polyisobutylene reaction product in oil resulted and analyzed 3.94% S and 2.22% P.

EXAMPLE III.PURIFICATION OF HYDROLY ZED P S -POLYISOBUTYLENE REACTION PRODUCT 500 g. of the hydrolyzed reaction product of Example I was dissolved in 800 ml. of mixed hexanes and extracted three times with 150 ml. portions of water. The water extracts gave negative phosphorus tests. The mixture was placed in a distillation flask and the hexane was stripped at a pressure of 20 mm. Hg and a temperature of 200 F. The yield was 493.0 g. analyzing 2.20% P and 0.82% S.

EXAMPLE IV.REACTION OF HYDROLYZED P 5 OLEFIN REACTION PRODUCT WITH TETRA- ETHYLENE PENTAMINE 250 g. of the purified product of Example III was mixed with 16.8 g. of tetraethylene pentamine /2 rnol amine per gram atom P). The mixture was heated to about 300 F. and held for 18 hours. The mixture was then stripped for 30 minutes at 500 F. under vacuum, yielding 265.4 g. of amine derivative which analyzed 2.06% P, 1.02% S and 2.18% N.

EXAMPLE V.REACTION OF P S -OLEFIN HY- DROLYZED REACTION PRODUCT WITH TRI- ETHYLENE TETRAMINE 250 g. of the purified product of Example III was reacted with 13.0 g. /2 mol per gram atom P) of triethylene tetramine. The same procedure was used as in Example IV. The yield was 261.3 g., analyzing 2.13% P and 0.99% S.

EXAMPLE VI.-REACTION OF UNHYDROLYZED P S -OLEFIN REACTION PRODUCT WITH TRI- ETHYLENE TETRAMINE 135 g. of a P S -polyisobutylene reaction product was fixed with g. of mineral lubricating oil and 13.2 g. of triethylene tetrarnine in a 500 ml. 3-nick flask equipped with a stirrer, reflux condenser, thermometer and a temperature contrtoller. The mixture was blanketed with nitrogen, heated to 300 F. and held with stirring for 18 hours. The mixture was then stripped to a bottom temperature of 400 F. at 5 mm. Hg for 15 minutes. Yield was 260.3 g. of a product analyzing 2.20% P, 2.70% S and 1.78% N.

EXAMPLE VII 249.8 g. of the product of Example VI was placed in a flask, blanketed with nitrogen and heated to 300 F. Water was added dropwise until H S evolution ended. The mixture was allowed to stand for 2 hours, then the product was stripped for 30 minutes at 300 F. under a pressure of 5 mm. Hg. Yield was 247.3 g. of material which analyzed 2.11% P, 1.62% S and 1.70% N.

Tests chosen to illustrate the elfectiveness of the lubricant compositions of the present invention were an Oxidator Test, a Caterpillar L1, Supplement-1 Test, a Falex E. P. Wear Test and an L-4 CuPb Strip Corrosion Test.

The Catalyzed Oxidator Test indicates the effectiveness of the additives of this invention as oxidation inhibitors. In this test 5% by weight of each amine derivative was dissolved in an acid refined naphthenic oil. A metal catalyst solution was added to the compositions. A portion of each such composition was heated to 340 F. and held at that temperature with constant stirring while oxygen was bubbled through the mixture at a rate suflicient to maintain saturation. The time required for 100 ml. of oil to absorb 1000 ml. of oxygen was observed and noted as Oxidator life. The results of these tests are noted in Table I. The additives were amine derivatives of hydrolyzed and unhydrolyzed P S -polyisobutylene reaction products from polyisobutylene having a molecular weight of 915.

TABLE I Oxidator life Amine derivative: (hrs) Base oil alone Ethylene diamine with unhydrolyzed P 8 polyisobutylene Diethylene triamine with hydrolyzed P S -polyisobutylene 12.4 Triethylene tetramine with hydrolyzed P 8 polyisobutylene 15 6 It is thus apparent from the above data that the additives of this invention function as effective oxidation invhibitors.

An L-1 Supplement 1 Caterpillar Engine Test was used to evaluate the detergency characteristics of the lubricant compositions. Reference to this test may be found in Coordinating Research Council Report No. L-1-545. Briefly the test involves use of the subject lubricant in the crankcase of a specially designed single-cylinder diesel engine. The engine is operated at a fixed speed and B.t.u. input with a fuel containing 1% sulfur by weight. The test was performed under the following conditions.

Test time and 60 hrs. Engine speed 1000 r.p.m. L-l0. Engine load Fuel input equal to 2950 :50 B.t.u. per minute. Jacket coolant temperatures:

Outlet 175 to 180 F.

Inlet 10 to 15 F. below outlet temperature.

Oil temp. to bearings to F.

Oil change None.

5 on a scale of -100 with 0 indicating no deposit and 100 a completely filled groove. The extent of discoloration of the lands and skirt are expressed, respectively, as L and PD and skirt PD (PD meaning piston discolorduced a prolonged reaction period with the simple salts initially formed, a reaction was performed in the following manner:

EXAMPLE VIII ation). These numbers are assigned on a scale of 0-800 with 0 indicating completely clean and 800 completely 1400 g. of a dithiophosphoric acid produced by the blackened. The base oil used in the test was a solvent hydrolysis of the product of P 8 and polyisobutylene was refined, waxy California crude having a viscosity index placed in a flask equipped as in the prior examples with of 85. The additives used were amine derivatives of a 85 g. of tetraethylene pentamine (ratio of combining hydrolyzed P S -polyis-o'butylene reaction product which weights equal 2 acid to l amine). The mixture was heated was produced from a polyisobutylene having a molecular with stirring for /2 hour below 150 F the temperature weight of about 915. The data from these tests are shown was then raised to 150 F. and a sample was withdrawn; in Table II. the temperature was then raised to 300 F., Sample 2 was TABLE II G.D. Nos. Land PD Nos. Skirt Test Lubricant PD Duration Nos.

Ring 1 Ring 2 Ring 3 Ring 4 Land 1 Land 2 Land 3 60 hrs Base Oil 10 10 8 3 750 700 600 10 120 hrs o 20 10 17 755 800 800 60 hrs Base oil plus 1% Tetraethylene pentamine deriva 3 1 0.06 0 45 30 15 15 60 hrs Bri in plus 1% Trialkylene tetramine derivative. 11 3 1 0.2 240 85 7O 10 120 hrs Base oil plus 1% Triethylene tetramine derivative. 10 2 1 0. 4 150 40 85 0 From the above data it is apparent that the compositaken. The temperature was maintained at 300 F. for a tions give improved detergency characteristics and are period of 24 hours and samples were withdrawn at the especially suitable for use in diesel service. following incremental periods after reaching 300 F.: L 4 Copper Lead Strip Corrosion Tests were performed Sample 3-1 hour; Sample 4-2 hours; Sample 55 upon the amine-P S -polybutene derivatives, as well as 30 hours; Sample 6-11 hours; Sample 717 hours; and uncompounded base oil. The base oil used in these tests Sample 8 24 hou was an acid refined SAE 30 grade having a viscosity index The material obtained in the preceding preparation of 85 derived from California waxy crude. These tests were subjected to the Falex Wear Test, as previously were conducted by immersing highly polished sections of described, also at 5% additive concentration levels. The a copper-lead bearing insert measuring about 2%" x base oil was a SAE 30 lubricating oil stock. X 1" and having a known weight in the test oil. The oil Oils containing the materials were also subjected to an was then heated to 500 F. and maintained at that temuncatalyzed Oxidator Test which is similar to the Oxidator perature with constant stirring for a period of 20 hours. Test described in column 4 except that no metal catalyst The strip was then removed from the oil and cleaned first solution is added. The following Table IV gives results of with chloroform and then with petroleum ether. The strip these tests:

was then weighed and the difference from the original weight of the strip was recorded as corrosion weight loss in milligrams. Table III embodies these results.

TABLE III [Cu-Pb strip corrosion data] Additive Weight Loss Base oil alone 124.0

(A) Amine (B) P s polyisobutylene Ethylene diamine Unhydrolyzed 0.3 Diethylene triamine do 4. 5

Do Hydrolyzed- 13. 1 Triethylene tetramin Unliydrolyze 4. 7

Do Hydrolyzed 15.2

The Falex Wear Test is described in Journal of the Institute of Petroleum, vol. 32, April 1946. The test assembly comprises a steel rod inserted between two steel V-shaped bearing blocks. The assembly of bearing blocks and rod is immersed in the lubricant composition being tested, the temperature of the lubricant being held at 210 F. throughout the 30-minute test period. A force of 440 lb. is applied to the shaft through the V-shaped bearing blocks. The shaft is weighed before and after the test to obtain weight loss. This test was performed using 5% by weight of the ethylene diamine derivative of P S -polyisobutylene reaction product.

The base oil used in this test shows a Weight loss of 5660 mg. Addition to 5% of the above additive resulted in reducing the loss to 7.8 mg., showing that the herein described compositions display extremely good E.P. characteristics.

In order to show the comparison of the materials pro- TABLE IV Reaction Time Falex Wear Uncatalyzed Sample No. Test, Weight Oxidator Test Hrs.) Loss (mg) (Hrs) 1 Failed, Pin Sheared.

Thus, it may be seen from data in the-above table that the oil composition containing the simple salt failed completely to pass the Falex Test, producing such friction that the pin sheared, while the materials produced with longer reaction periods produced excellent results, for example, Sample 6 giving only 3.8 mg. wear. Also it may be noted that extended periods in the Uncatalyzed Oxidator Test were obtained for the subject materials in comparison with the simple salts.

The additives of this invention are effective in a wide variety of oils of lubricating viscosity and in blends of such oils, Thus, the base oil can be a refined Pennsylania or other parafiin base oil, a refined naphthenic base oil or a synthetic hydrocarbon or non-hydrocarbon oil of lubricating viscosity. As examples of the synthetic oils there can be mentioned alkylated waxes, alkylated hydrocarbons of relatively high molecular weight, hydrogenated polymers of hydrocarbons and condensation products of of chlorinated alkyl hydrocarbons with aryl compounds. Other suitable oils are those which are obtained by polymerization of lower molecular weight alkylene oxides, such as propylene and/ or methylene oxide. Still other synthetic oils are obtained by etherification and/ or esterification of the hydroxy groups and alkylene oxide polymers, such as, for example, the acetate of the Z-ethylhexanol-initiated polymer of propylene oxide. Other important classes of synthetic oils include the various esters as, for example, di-(Z-ethylhexyl) sebacates, tricresyl phosphate and silicate esters. Mixtures of synthetic and mineral oils are also suitable as bases. However, in the preferred embodiment of the invention mineral oil bases are used.

Lubricant compositions within the purview of this invention are those that, in addition to the herein described amine-phosphorus sulfide-polyolefin adjuvants, contain other additives known in the prior art and which contribute specific, desired properties. Illustrative of the types of additives contemplated are pour point depressants, oiliness and extreme pressure agents, blooming agents, thickening agents and compounds which enhance the temperature-viscosity characteristics of the oil, i.e., V.I. improvers. In addition, the invention contemplates using compositions of supplementary detergents, oxidation inhibitors, anticorrosion and antiwear agents.

Illustrative lubricant compositions of the aforementioned type containing the detergent additive of this invention as well as other agents may include, for example, from about 0.1 to 10% by weight of alkaline earth higher alkyl phenate detergent and wear resisting agents, such as calcium alkyl phenates having an average of approximately 14 carbon atoms in the alkyl group, as Well as organic th-iophosphate corrosion and high temperature oxidation inhibitors, such as the reaction product of pinene and P 8 and the bivalent metal dihydrocarbyl dithiophosphates, zinc butyl hexyl dithio-phosphate and Zinc tetradecyl phenyl dithiophosphate, in amounts of from about 0.1 to by weight. V.I. improvers which may be employed in the compositions, usually in amounts of from about 1 to 10% by weight, include, by way of example, the homopolymers of alkyl methacrylates, such as the dodecyl methacrylate polymers known to the trade as Acryloid 710 and Acryloid 763, products of Rohm & Haas Co., and high molecular weight butene polymers, such as Paratone, Enjay 15P, a product of the Enjay Company.

The lubricant compositions may contain from 0.001 to 10% by weight of the additives of this invention. The preferred range, however, is between 0.5% and 5% by weight.

We claim:

1. A lubricant composition having improved detergency, antioxidant and antiwear properties consisting essentially of a major proportion of a mineral lubricating oil and a minor proportion, from 0.01 to 10%, of the prodnot obtained by reacting in proportions sufficient to effect substantial neutralization, at a temperature from 200 F. to 500 F., for a period of from 4 to 30 hours,

(A) a phosphorus sulfide-polybutene reaction product or a hydrolyzed phosphorus sulfide-polybutene reaction product, and

(B) a polyamine represented by the general formula wherein x is an integer from 1 to 9 and in which the phosphorus sulfide-polybutene reaction product is produced from polybutene, having a molecular weight of from 500 to 1500, said product having an IR analysis diiferent than that obtained with simple amine salt analogs.

2. The composition of claim 1, in which the polybutene has a molecular weight of from 750 to 1000.

3. The composition of claim 1, in which the phosphous Sulfide is phosphorus pentasulfide.

4. The composition of claim 3, in which the amine and phosphorus pentasulfide-polybutene product are reacted for a period of from 4 to 24 hours.

5. The composition of claim 4, in which the reaction temperature is about 300 F.

6. The product obtained by reacting in proportions suflicient to effect substantial neutralization, at a temperature of from 200 F. to 500 F., for a period of from 4 to 30 hours,

(A) a phosphorus sulfide-polybutene reaction product or a hydrolyzed phosphorus sulfide-polybutene reaction product and (B) a polyamine represented by the general formula NH (CH -CH -NH -H wherein x is an integer from 1 to 9 and in which the phosphorus sulfide-polybutene reaction product is produced from polybutene, having a molecular weight of from 500 to 1500, said product having an IR analysis different than that obtained with simple amine salt analogs.

7. The product of claim 6, wherein the polybutene has a molecular weight of from 750 to 1000.

References Cited UNITED STATES PATENTS 2,809,934 10/1957 Alford et al. 252-327 2,849,398 8/1958 Moody et a1. 25232.7 2,907,713 10/1959 Lemmon et al 25232.7 3,143,506 8/1964 Schallenberg et al. 25232.7

DANIEL E. WYMAN, Primary Examiner.

L. G. XIARHOS, Assistant Examiner. 

1. A LUBRICANT COMPOSITION HAVING IMPROVED DETERGENCY, ANTIOXIDANT AND ANTIWEAR PROPERTIES CONSISTING ESSENTIALLY OF A MAJOR PROPORTION OF A MINERAL LUBRICATING OIL AND A MINOR PROPORTION, FROM 0.01 TO 10%, OF THE PRODUCT OBTAINED BY REACTING IN PROPORTIONS SUFFICIENT TO EFFECT SUBSTANTIAL NEUTRALIZATION, AT A TEMPERATURE FROM 200*F. TO 500*F., FOR A PERIOD OF FROM 4 TO 30 HOURS, (A) A PHOSPHORUS SULFIDE-POLYBUTENE REACTION PRODUCT OR A HYDROLYZED PHOSPHORUS SULFIDE-POLYBUTENE REACTION PRODUCT, AND (B) A POLYAMINE RPRESENTED BY THE GENERAL FORMULA 